The U.S. Senate today will debate why women still earn roughly 80 cents to a man's dollar. Equal pay is a goal of the Paycheck Fairness Act. As NPR's Jennifer Ludden reports, one part of the bill would ban workplace policies that keep everyone's pay secret.

JENNIFER LUDDEN, BYLINE: Yes, experts say people do still get fired or punished for talking about their pay. It may not happen often. In fact, federal labor law already deems it illegal. But a lot of companies still make people sign a paper promising to keep quiet, and threaten dismissal if they don't.

ARIANE HEGEWISCH: It was quite surprising how many people are either prohibited or discouraged from discussing pay. It's over 60 percent of workers in the private sector who say that.

LUDDEN: That's Ariane Hegewisch of the Institute for Women's Policy Research, which asked the question. Hegewisch says this makes it hard to get at that part of the gender pay gap researchers think is still due to plain, old discrimination, even if it's unconscious.

HEGEWISCH: You know, assumptions, biases; it's inside. It's not explicit. But if you have transparency, the research is there that the bias becomes much less. The differences disappear.

EMILY MARTIN: Pay discrimination often is secret because you don't know how your salary stacks up.

LUDDEN: Emily Martin is with the National Women's Law Center.

MARTIN: To know you're being paid less than the man across the hall, you'd have to be able to have that conversation.

LUDDEN: But do people really want to talk about their pay?

MIKE AITKEN: You know, if you were to ask even some of your colleagues at NPR would you want your pay information disclosed, I think the answer would be no.

LUDDEN: Pay is private, says Mike Aitken of the Society for Human Resource Management. While his group opposes the Paycheck Fairness Act, it's fine with not letting companies mandate pay secrecy. Still, Aitken says employers may have valid reasons for paying someone more, and he says too much transparency is a bad thing.

AITKEN: Because of the potential strife and uneasiness that it could cause, it might impact employee engagement. It could certainly prompt potential lawsuits.

LUDDEN: No one expects the Paycheck Fairness Act to pass in the current, polarized Congress, but states are moving ahead. Last year, New Jersey became the seventh state to explicitly give workers the right to disclose, discuss and compare their paychecks.